books.google.it - Polyvinyl chloride (PVC) has been around since the late part of the 19th century, although it was not produced commercially until the 1920s; it is the second largest consumed plastic material after polyethylene. PVC products can be rigid or flexible, opaque or transparent, coloured, and insulating or...https://books.google.it/books/about/Practical_Guide_to_Polyvinyl_Chloride.html?hl=it&id=8j3elWO9ebcC&utm_source=gb-gplus-sharePractical Guide to Polyvinyl Chloride